Automatic cut-out for electric incandescent lamps



Oct. 16, 1928. 1,687,530

l'. H. VAN HORN x-:r m.

AUTOMATIC CUT- our PoR EnEcTRxc INcANDEscENT LAMPS me@ March 11, 1924 .52. a/Mh THEIR AT1-'0H NEI.

Patented oa. 16, 192s.

UNITED STATES* ,y .l f ,1,687,530 PATENT OFFICE.

I IRVING IH. VAN HORN AND WILBUR A. PIPKIN, OE EAST CLEVELAND, OHIO, AS- 'SIGNOBS TO' GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

' AUTOMATIC CUT-OUT FOR ELECTRIC INCANDESCENT LAMPS.

Application led March 11, 1924. Serial No. 698,502

Our invention relates to series electric incandescent lamps and more particularly to means for preventing the extinguishment of all the lamps in the series upon the failure of any one lamp. Heretofore one way of ,taking care of this situation was to arrange the `conducting supports ofthe filament so that portions. thereof were very close together. It was necessary to-have the conl0 ductors close enough together so that upon a failure of the filament during use and .the-consequent arcing that the molten mass produced by the fusing of the filament supporting conductors would bridge the gap therebetween and provide a conductive path through the lamp which would preserve the circuit for the other lamps of the series and thus prevent their extingalishment. On the other hand it was necessary to separate the conductors far enough so that there would normally be no rcing which would short circuit the filament. In order to fix this distance it has been considered desirable to provide an insulating separator engaging and holding the conducting supports ata definite distance apart. While such an arrangement takes care of the condition created by the failure of a lamp during use, it does not take care of the condition created by the failure of a lamp when not in use. Such a failure results in the lamps subsequently failing to light and there 1s inconveniencein locating the particular lamp which is causing the trouble.v Our invention provides means for taking care of both of the aforesaid conditions for, according to our inven? tion. the device which spaces the conductors, while normally insulating, becomes conduca -ftive if there is a; broken filament in the dey40 vi'ce when the current is turned on. -A In the drawing, Fig. 1 is an elevation of va series electric incandescent lamp;,Fig. 2

is aside elevation of parts thereof; Fig. 3A

isa partial elevation of such a series electric incandescent lamp in which the filament has vbeen broken; Fig. 4 is an elevationof a por-- tion of a lamp showing lthe operation of our invention under onecondition; Fig. 5 is apartial horizontal section showing our improved separator or cut-out; Fig. 6 is a perspective thereof; and Fig. Tis a vertical section thereof.

As shown in Fig. 1, the incandescent lamp comprises the bulb 10 having thel usual base '55 11 and stem 12 in which are sealed the leadl ing-in conductors and filament supports-13 and 14, The filament 15 is mounted at the ends of the supports 13 and 14. In Figs. 5, 6` and 7 are shown the spacing member 16 which is shaped to engage the filament lconducting supports 13 land 14.l Preferably this member isa s'o-called film cut-out and is composed of sheet aluminum 17 coated "with a thin. film of aluminum oxide 18.

metal which finally coalesce as shown in Fig.v 4, when they reachthe separator 16. 4This provides a .conductive path through the lamp completing the circuit for the other -lamps in the series and prevents their extinguish` ment.

If the filament 15 breaks when the .lamp is not in use, the film cut-out operates when the circuit switch is closed. The full voltage of the line beingacross the film cut-out, the

4film of aluminum oxide is puncture'd and a i conductive path provided. This allows the other lamps of the series to light up and at the Sametime shows up the defective lamp.

It will be obvious that various film cut-Y outs may be substituted for that specifically Vhereinbefore referred to.

What we claim as new and desire to secure by Letters Patent of the United States, is:

1. In an electric incandescent lamp, the combination of a bulb containing a non-oxidizing atmosphere7 a filament mounted within said bulb,va stem sealed within said bulb,` a pair of conductive supports for said filament sealed in the inner end of said stem, l

'and av member consisting of a conductive .supporthaving thereon a coating of insulaterminals, the combinationl of a filament surlrounded by a non-oxidizing atmosphere, a

pair of conductive supports therefor connected to the lamp terminals, and an oxide coated conducting member disposed between said portions and serving to hold portions of said conductive supports in close proximity to each other.

3. In an electric incandescent lamp having terminals, the combination of a filament consistingr of a single strand surrounded by a non-oxidizing atmosphere, a pair of contions and serving to hold portions of said 15 conductive supports in close proximity to each other.

Infvvitness whereof, We have hereunto setr our hands this Sthday of March, 1924.

IRVNG H. VAN HORN.

WILBUR A. PIPKIN. 

